Process of extracting tin from base bullion.



UNITED STATES PATENT OFFICE.

BRIAN CHARLES BESLEY, OF HOWELL, NEW SOUTH WALES, AUSTRALIA PROCESS OFEXTRACTING TIN FROM BASE BULLION.

No Drawing.

To all whom, it may concern:

Be it known that I, BRIAN CHARLES BES- LEY, a subject of the King ofGreat Britain and Ireland, residing at Howell, in the State of New SouthWVales, Australia, have invented certain new and useful Improvements inProcesses of Extracting Tin from Base Bullion, of which the following isa specification.

My invention relates to the extraction of tin from lead or base bullionand it consists in a process in which the tin is extracted therefrom asan oxid by means of an oxid of lead.

The process may be conducted in a pot or crucible but in practice it isconducted on a large scale in a furnace of the reverberatory type. Rocksalt or common salt is introduced into the furnace and brought to aliquid condition therein by raising and maintaining the temperatureabove its fusion point. For salt, borax may be substituted, but borax isobjectionable on account of its relatively high cost and because itforms a slag with the bullion, fro-m which slag the borax cannot berecovered economically. In practice rock salt is preferred be cause ofits relatively low cost.

The base bullion is introduced into the bath of molten salt in thefurnace by dropping it into the same in a solid condition, or it may becured in a molten condition into the bath. The bullion sinks in thebath, thev molten salt forming a cover, which should be of substantialdepth, preferably about four inches. This cover prevents volatilizationand oxidation of the bullion by atmospheric contact and consequent lossof lead and silver. The salt bath and the bullion contained in it beingmaintained in a fused condition, the oxid of lead, litharge or red lead(litharge preferably) is thrown into the furnace. About two weights oflitharge or red lead are used to each weight of tin in' the bullion, buta greater or less Specification of Letters Patent.

Application filed June 21, 1912.

Patented Apr. 29, 1913.

Serial No. 705,112.

proportion within a reasonable range will be eifective. After a periodof about half an hour during which time the tin becomes associated withthe lead oxid and leaves the molten lead, the furnace is tapped and themolten lead carrying the silver contents of the bullion is run off intomolds, the salt is run off and saved, and the tin lead oxid is drawn outin lumps. Then another charge may be treated in. the furnace, the saltsaved from the previous run being reused. The lead-silver productcontains only a trace of tin. The tin-lead oxid is reduced by smeltingin a'reducing atmosphere in a blast furnace with coke and slag obtainedfrom the lead smelting furnace in which the bullion was produced. Amarketable product in the shape of a tin-lead solder is thus obtained.WVhen the process is conducted on a small scale in a pot or crucible,the products are found in separate strata after cooling and may bereadily separated by breaking the layers apart.

What I claim as my invention and desire to secure by Letters Patent is:

1. The process of treating base bullion which consists essentially inseparating tin therefrom by fusing the bullion with an oxid of lead in afused bath of neutral material which excludes atmospheric contact, andseparating mechanically the metallic lead and the tin-lead oxid.

2. The herein described process of extracting tin from base bullion,which consists in fusing the bullion with an oxid of lead under a coverof molten salt, tapping off the lead, withdrawing the tin-lead oxid, andsmelting or reducing said oxid to metal for the production of a tin-leadalloy.

In testimony whereof I have affixed my signature in presence of twowitnesses.

BRIAN CHARLES BESLEY.

Witnesses:

S. BECK, lV. J. DAVIS.

copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. C.

